Lighting unit and reflector therefor



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Patented Feb. 7, 1928.

UNITED STATES PATENT OFFICE. f

CROMWELL A. B. HALVORSON, JR., OF LYNN ,i MASSACHUSETTS, SSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

LIGHTING UNIT nuny REFLECTOR THEREFDR.

Application led September 2, 1924. Serial No. 735,248.

My invention relates to lightingunits and reflectors. More in particular, the invention relates to that type of unit and reflector which is especially adapted for use in the field of highway lighting. Heretofore, `lighting units have been provided with refracting elements for the purpose of controlling the light distribution of the unit. These refractor elements have usually been in the form of prisn'iatic glass elements. Elements of this type are -quite expensive and also subject to fracture. I have found, however, that suitable light distribution may be produced with lighting units by using reflectors instead of refr-actors. Ordinarily, a reflector in a lighting unit would produce a dark background which would interfere with the illumination ofthe enclosing globe'of the unit. I have found, however', that this objection can be avoided by providing a reflector with a large number ofv comparatively small openings or perforations i through which a small percentage of the flood of light within the area covered by the reflector may sift through and light up the background of the reflector.

It is also an object of the inventionto fill in the perforations with some transparent light diffusing material such as a lacquer or,

in some instances, glass, in order to avoid the formation of objectionable shadow outlines due to the perforations. The perforations in these reflectors may be designed to allow, for example, 10% of the light subtended by the 5 reflector to pass through.

The details of my invention `are hereinafter more fully set forth and claimed, ref erence being had to the accompanying'drawings in which Fig. 1 shows the unit in ele- '0 vation and partly in section, a perforated reflector being also shown; Fig. 2 shows one form of the perforation in perspective; Fig. 3 shows a plan and side View of another form of reflector; Fig. 4 is a section along the lower rim of the reflector of Fig. 2 showing how the rim may be serrated to avoid the formation of a sharp rim shadow on the globe or other background of the reflector; Fig. 5 is a section on m-- of Fig. 4 showing 5U the coat of transparent ydiffusing' material such as a lacquer covering the perforations; and Fig. 6 is a section of a form of reflector in which a glass surface with protuberances is coated along the interstices or depressions with a reflecting metal such as silver.

` Referring more in detail to the drawings, will be seen that the globe 2 encloses the light source 3 and is supported by the. canopy 4. The globe is arranged to swing about any suitable form of hinge 5 and tobe held in closed position by any suitable forni of latch 6. lVithin the unit there is provided a ,socket of any suitable type, not shown, for

receiving the lamp 3. lVithin the globe there is provided a reflector 7 which has a central opening through which the neck of the lamp 3 extends. About the lamp 3 there is provided one form that is an elipsoidal form of perforated reflector 8 which may be secured in place in any suitable manner. As shown, the upper rim 9 of the reflector is spun over the inner rim of the reflector 7 and is thus held in position. Theconstruction of the'reflector 7 is such that when the globe is unlatched and lowered `about the hinge 5 the reflector 7 is permitted to settle until the r perforated reflector 8 rests upon the lamp 3, which latter serves as support for both re flectors while the globe 2 is down'. As the globe is raised and returned to its closed position the outer rim of the reflector 7 engages the rim of the globe 2 and is thus picked up again and raised into position thereby bringing the perforated reflector 8 also into position. With this type of reflec- 85 tor the light passes through the perforations and falls on the outer enclosing globe 2 of the unit which is preferably of the diffusing type and which mayl also be of the ripple type. The light that passes through the no perforations, therefore, enables the outline of the globe to be seen at night. The diffus ing lacquer 10 may be for example, glyptal. Or, as indicated in Fig 6, it may be glass or any other suitable transparent medium. *Q5 The formation of any objectional shadow outlines due to the perforations can thus be avoided. The same result may be accomplished by the use of a reflector made of thin, blown or pressed glass having on the 10U outer surface prismatic elements such as beads, ripples or any other suitable form of prismatic protuberance 11 which will allow a small amount of light, 10% for example, to pass through. This light, of course, will los be over the inside of the globe and in this way avoid the formation of objectionable images of the perforations. The space between the prismaticprotuberances may be first coveredwith a silver layer 12. A perlio forated ina-t is then applied over the reflector in `such manner that the protuberancee project through the perforations in the mat to enable the protuberances to be brushed eleanfoftlie silver depositQThe silver may be protected, as is Well ln'owln by av coat 'ot It will be understood that the distribution of light may be Varied by'varying the lshape:

of the reflector, which latter may have the form of the surface of revolution producedby `rotating in any one ol' the conics; t In fact,` the surface ol a rel'leetornmy assume the form-of any curved surface `aborda-the axisof the unit; t ,i i f i :l

A `unit of the type contemplated 11h19,",

therefore, be` constructed to giveY any suit-l abletype ofy light distribution aboutjthe axis of the unit, whlehdistribution may be eynimetrical or asymmetrical. v

It will be understood that the" principles of 4my invention may be applied in orins otheru than these Speeilic concrete forms shown and described which will readily sug-` gest thelnselves in i View of the disclosure Without departlng Atroni the spiritlor Athe invention or from the scope `ottlle-claiinev herein.

That claim as new and'desire to secure by Letters Patent of" the United States, 1s 1. A reflector' consisting of a body oftransparent material provided With a multiplicity of protuberanees and a layer of a metallic 4rellectinginaterial over the outer surface or said body through which the said protuber ancesprojeet. whereby rays of light from a source located Within the reflector which strike the metal may be reflected" back through the transparent material and whereby other rays `of light may pass through the transparent material and through -the protuberanees beyond the reflector. y

:LA reilector coneistiug ol' a body of transparent material provided with a` multiplieityoi" protuberances and a layer of a metallic reflecting material over the outer surilaee o'l said body tluough which the "said ln-otuheraneee project rwhereby rays ol light from a source located Within the reflector which strike the metal may be reflected haelt through thetransparent,material and wher@l by other-rays ol'` light may pass through the 4traneparent vnn'iterial y and through the` protuberanees beyond the reflector, the` said i relier-,tor being inthe l'orin o an asymmetric surface of revolutionflvhereby theretlected lightis asymmetrieally distributed Vabout the` anis of the `rettet-tor. l t

ln Wit-ness Wluereolf,` l have hereuntoset my handthis 26th day'o August, 192i. t

u orzoMWELL a; e; HALVoRsoN, Jjn. 1 

